I noticed recently that every morning my car sits lower than when I shut off the car the night before. When I start the car in the morning, the suspension raises a bit. Is this normal?

 

It happens to many abc equipped MB's but you should not consider it normal. It is a sign you have contamination in your valve block.

 

Thanks for the quick reply! Is this an expensive fix?

 

Borntotravel...the symptom you describe is common on the MB models with ABC, particularly as they age. In a nutshell, when the engine is shut off the valves in the valve blocks should seal completely so that the weight of the car does not force any fluid past the closed valves...thus the "sag" does not occur. Through use, wear, natural properties of the fluid, etc. the valve seals can become less than 100%. Worn o-rings are one cause, dirty/contaminated fluid is another cause as BlownV8 commented. When you start the engine and the pump takes over the car goes back to normal height. Imo, it is not an immediate concern. Some people do the home-style flush and change the filter. Ironically, if you have contaminants in the fluid this can cause the sag to worsen OR improve, depending on how the contaminants shift around the o-ring seals. Without knowing the history of your car, I like the idea of having an independent mechanic do the rodeo routine and flush the abc fluid and change the filter. I do not know the year the filters changed but the first generation abc filters were 10 microns; they changed to 3 microns somewhere on the path so always good to know you have the latest, most restrictive filter.

The blocks/seals can be reconditioned. Basically clean them out and put new o-rings. Many have commented sag disappeared after that. Cost if you get someone to do it...around a few hundred dollars. If you are handy you can open up the valve yourself. The front valve, to me, is easier to remove. Some say the rear is easier...but one or two of the hoses can be challenging to remove. There is a quick release tool that will separate the hydraulic hoses...probably a worthwhile investment if you decide to go down the path of removing the valve blocks.

For $300-$400 you can probably get an indy to do the rodeo and flush/filter. It may solve the sag, at least for a while. The abc suspension is a hydraulic system. Using it is the best way to keep it functioning. Also cycle through the height adjustments periodically to keep those valves moving freely.

Below is a link to an informative blog concerning the ABC. Mark

http://mercedes-abc-drive-carefully....y-part-of.html

 

thanks for everyone's replies!!